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fs/ntfs3: Refactoring attr_set_size to restore after errors
authorKonstantin Komarov <almaz.alexandrovich@paragon-software.com>
Wed, 13 Jul 2022 15:00:03 +0000 (18:00 +0300)
committerKonstantin Komarov <almaz.alexandrovich@paragon-software.com>
Wed, 3 Aug 2022 15:25:09 +0000 (18:25 +0300)
Added comments to code
Added two undo labels for restoring after errors

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
fs/ntfs3/attrib.c

index 5ba83eb..c29b2de 100644 (file)
@@ -173,7 +173,6 @@ int attr_allocate_clusters(struct ntfs_sb_info *sbi, struct runs_tree *run,
 {
        int err;
        CLST flen, vcn0 = vcn, pre = pre_alloc ? *pre_alloc : 0;
-       struct wnd_bitmap *wnd = &sbi->used.bitmap;
        size_t cnt = run->count;
 
        for (;;) {
@@ -196,9 +195,7 @@ int attr_allocate_clusters(struct ntfs_sb_info *sbi, struct runs_tree *run,
                /* Add new fragment into run storage. */
                if (!run_add_entry(run, vcn, lcn, flen, opt == ALLOCATE_MFT)) {
                        /* Undo last 'ntfs_look_for_free_space' */
-                       down_write_nested(&wnd->rw_lock, BITMAP_MUTEX_CLUSTERS);
-                       wnd_set_free(wnd, lcn, flen);
-                       up_write(&wnd->rw_lock);
+                       mark_as_free_ex(sbi, lcn, len, false);
                        err = -ENOMEM;
                        goto out;
                }
@@ -419,40 +416,44 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
        struct mft_inode *mi, *mi_b;
        CLST alen, vcn, lcn, new_alen, old_alen, svcn, evcn;
        CLST next_svcn, pre_alloc = -1, done = 0;
-       bool is_ext;
+       bool is_ext, is_bad = false;
        u32 align;
        struct MFT_REC *rec;
 
 again:
+       alen = 0;
        le_b = NULL;
        attr_b = ni_find_attr(ni, NULL, &le_b, type, name, name_len, NULL,
                              &mi_b);
        if (!attr_b) {
                err = -ENOENT;
-               goto out;
+               goto bad_inode;
        }
 
        if (!attr_b->non_res) {
                err = attr_set_size_res(ni, attr_b, le_b, mi_b, new_size, run,
                                        &attr_b);
-               if (err || !attr_b->non_res)
-                       goto out;
+               if (err)
+                       return err;
+
+               /* Return if file is still resident. */
+               if (!attr_b->non_res)
+                       goto ok1;
 
                /* Layout of records may be changed, so do a full search. */
                goto again;
        }
 
        is_ext = is_attr_ext(attr_b);
-
-again_1:
        align = sbi->cluster_size;
-
        if (is_ext)
                align <<= attr_b->nres.c_unit;
 
        old_valid = le64_to_cpu(attr_b->nres.valid_size);
        old_size = le64_to_cpu(attr_b->nres.data_size);
        old_alloc = le64_to_cpu(attr_b->nres.alloc_size);
+
+again_1:
        old_alen = old_alloc >> cluster_bits;
 
        new_alloc = (new_size + align - 1) & ~(u64)(align - 1);
@@ -475,24 +476,27 @@ again_1:
                mi = mi_b;
        } else if (!le_b) {
                err = -EINVAL;
-               goto out;
+               goto bad_inode;
        } else {
                le = le_b;
                attr = ni_find_attr(ni, attr_b, &le, type, name, name_len, &vcn,
                                    &mi);
                if (!attr) {
                        err = -EINVAL;
-                       goto out;
+                       goto bad_inode;
                }
 
 next_le_1:
                svcn = le64_to_cpu(attr->nres.svcn);
                evcn = le64_to_cpu(attr->nres.evcn);
        }
-
+       /*
+        * Here we have:
+        * attr,mi,le - last attribute segment (containing 'vcn').
+        * attr_b,mi_b,le_b - base (primary) attribute segment.
+        */
 next_le:
        rec = mi->mrec;
-
        err = attr_load_runs(attr, ni, run, NULL);
        if (err)
                goto out;
@@ -507,6 +511,13 @@ next_le:
                        goto ok;
                }
 
+               /*
+                * Add clusters. In simple case we have to:
+                *  - allocate space (vcn, lcn, len)
+                *  - update packed run in 'mi'
+                *  - update attr->nres.evcn
+                *  - update attr_b->nres.data_size/attr_b->nres.alloc_size
+                */
                to_allocate = new_alen - old_alen;
 add_alloc_in_same_attr_seg:
                lcn = 0;
@@ -520,9 +531,11 @@ add_alloc_in_same_attr_seg:
                        pre_alloc = 0;
                        if (type == ATTR_DATA && !name_len &&
                            sbi->options->prealloc) {
-                               CLST new_alen2 = bytes_to_cluster(
-                                       sbi, get_pre_allocated(new_size));
-                               pre_alloc = new_alen2 - new_alen;
+                               pre_alloc =
+                                       bytes_to_cluster(
+                                               sbi,
+                                               get_pre_allocated(new_size)) -
+                                       new_alen;
                        }
 
                        /* Get the last LCN to allocate from. */
@@ -580,7 +593,7 @@ add_alloc_in_same_attr_seg:
 pack_runs:
                err = mi_pack_runs(mi, attr, run, vcn - svcn);
                if (err)
-                       goto out;
+                       goto undo_1;
 
                next_svcn = le64_to_cpu(attr->nres.evcn) + 1;
                new_alloc_tmp = (u64)next_svcn << cluster_bits;
@@ -614,7 +627,7 @@ pack_runs:
                if (type == ATTR_LIST) {
                        err = ni_expand_list(ni);
                        if (err)
-                               goto out;
+                               goto undo_2;
                        if (next_svcn < vcn)
                                goto pack_runs;
 
@@ -624,8 +637,9 @@ pack_runs:
 
                if (!ni->attr_list.size) {
                        err = ni_create_attr_list(ni);
+                       /* In case of error layout of records is not changed. */
                        if (err)
-                               goto out;
+                               goto undo_2;
                        /* Layout of records is changed. */
                }
 
@@ -638,47 +652,56 @@ pack_runs:
                err = ni_insert_nonresident(ni, type, name, name_len, run,
                                            next_svcn, vcn - next_svcn,
                                            attr_b->flags, &attr, &mi, NULL);
-               if (err)
-                       goto out;
-
-               if (!is_mft)
-                       run_truncate_head(run, evcn + 1);
 
-               svcn = le64_to_cpu(attr->nres.svcn);
-               evcn = le64_to_cpu(attr->nres.evcn);
-
-               le_b = NULL;
                /*
                 * Layout of records maybe changed.
                 * Find base attribute to update.
                 */
+               le_b = NULL;
                attr_b = ni_find_attr(ni, NULL, &le_b, type, name, name_len,
                                      NULL, &mi_b);
                if (!attr_b) {
-                       err = -ENOENT;
-                       goto out;
+                       err = -EINVAL;
+                       goto bad_inode;
                }
 
-               attr_b->nres.alloc_size = cpu_to_le64((u64)vcn << cluster_bits);
-               attr_b->nres.data_size = attr_b->nres.alloc_size;
-               attr_b->nres.valid_size = attr_b->nres.alloc_size;
+               if (err) {
+                       /* ni_insert_nonresident failed. */
+                       attr = NULL;
+                       goto undo_2;
+               }
+
+               if (!is_mft)
+                       run_truncate_head(run, evcn + 1);
+
+               svcn = le64_to_cpu(attr->nres.svcn);
+               evcn = le64_to_cpu(attr->nres.evcn);
+
+               /*
+                * Attribute is in consistency state.
+                * Save this point to restore to if next steps fail.
+                */
+               old_valid = old_size = old_alloc = (u64)vcn << cluster_bits;
+               attr_b->nres.valid_size = attr_b->nres.data_size =
+                       attr_b->nres.alloc_size = cpu_to_le64(old_size);
                mi_b->dirty = true;
                goto again_1;
        }
 
        if (new_size != old_size ||
            (new_alloc != old_alloc && !keep_prealloc)) {
+               /*
+                * Truncate clusters. In simple case we have to:
+                *  - update packed run in 'mi'
+                *  - update attr->nres.evcn
+                *  - update attr_b->nres.data_size/attr_b->nres.alloc_size
+                *  - mark and trim clusters as free (vcn, lcn, len)
+                */
+               CLST dlen = 0;
+
                vcn = max(svcn, new_alen);
                new_alloc_tmp = (u64)vcn << cluster_bits;
 
-               alen = 0;
-               err = run_deallocate_ex(sbi, run, vcn, evcn - vcn + 1, &alen,
-                                       true);
-               if (err)
-                       goto out;
-
-               run_truncate(run, vcn);
-
                if (vcn > svcn) {
                        err = mi_pack_runs(mi, attr, run, vcn - svcn);
                        if (err)
@@ -697,7 +720,7 @@ pack_runs:
 
                        if (!al_remove_le(ni, le)) {
                                err = -EINVAL;
-                               goto out;
+                               goto bad_inode;
                        }
 
                        le = (struct ATTR_LIST_ENTRY *)((u8 *)le - le_sz);
@@ -723,12 +746,20 @@ pack_runs:
                                attr_b->nres.valid_size =
                                        attr_b->nres.alloc_size;
                }
+               mi_b->dirty = true;
 
-               if (is_ext)
+               err = run_deallocate_ex(sbi, run, vcn, evcn - vcn + 1, &dlen,
+                                       true);
+               if (err)
+                       goto out;
+
+               if (is_ext) {
+                       /* dlen - really deallocated clusters. */
                        le64_sub_cpu(&attr_b->nres.total_size,
-                                    ((u64)alen << cluster_bits));
+                                    ((u64)dlen << cluster_bits));
+               }
 
-               mi_b->dirty = true;
+               run_truncate(run, vcn);
 
                if (new_alloc_tmp <= new_alloc)
                        goto ok;
@@ -747,7 +778,7 @@ pack_runs:
                if (le->type != type || le->name_len != name_len ||
                    memcmp(le_name(le), name, name_len * sizeof(short))) {
                        err = -EINVAL;
-                       goto out;
+                       goto bad_inode;
                }
 
                err = ni_load_mi(ni, le, &mi);
@@ -757,7 +788,7 @@ pack_runs:
                attr = mi_find_attr(mi, NULL, type, name, name_len, &le->id);
                if (!attr) {
                        err = -EINVAL;
-                       goto out;
+                       goto bad_inode;
                }
                goto next_le_1;
        }
@@ -772,13 +803,13 @@ ok:
                }
        }
 
-out:
-       if (!err && attr_b && ret)
+ok1:
+       if (ret)
                *ret = attr_b;
 
        /* Update inode_set_bytes. */
-       if (!err && ((type == ATTR_DATA && !name_len) ||
-                    (type == ATTR_ALLOC && name == I30_NAME))) {
+       if (((type == ATTR_DATA && !name_len) ||
+            (type == ATTR_ALLOC && name == I30_NAME))) {
                bool dirty = false;
 
                if (ni->vfs_inode.i_size != new_size) {
@@ -786,7 +817,7 @@ out:
                        dirty = true;
                }
 
-               if (attr_b && attr_b->non_res) {
+               if (attr_b->non_res) {
                        new_alloc = le64_to_cpu(attr_b->nres.alloc_size);
                        if (inode_get_bytes(&ni->vfs_inode) != new_alloc) {
                                inode_set_bytes(&ni->vfs_inode, new_alloc);
@@ -800,6 +831,47 @@ out:
                }
        }
 
+       return 0;
+
+undo_2:
+       vcn -= alen;
+       attr_b->nres.data_size = cpu_to_le64(old_size);
+       attr_b->nres.valid_size = cpu_to_le64(old_valid);
+       attr_b->nres.alloc_size = cpu_to_le64(old_alloc);
+
+       /* Restore 'attr' and 'mi'. */
+       if (attr)
+               goto restore_run;
+
+       if (le64_to_cpu(attr_b->nres.svcn) <= svcn &&
+           svcn <= le64_to_cpu(attr_b->nres.evcn)) {
+               attr = attr_b;
+               le = le_b;
+               mi = mi_b;
+       } else if (!le_b) {
+               err = -EINVAL;
+               goto bad_inode;
+       } else {
+               le = le_b;
+               attr = ni_find_attr(ni, attr_b, &le, type, name, name_len,
+                                   &svcn, &mi);
+               if (!attr)
+                       goto bad_inode;
+       }
+
+restore_run:
+       if (mi_pack_runs(mi, attr, run, evcn - svcn + 1))
+               is_bad = true;
+
+undo_1:
+       run_deallocate_ex(sbi, run, vcn, alen, NULL, false);
+
+       run_truncate(run, vcn);
+out:
+       if (is_bad) {
+bad_inode:
+               _ntfs_bad_inode(&ni->vfs_inode);
+       }
        return err;
 }